Treatment process of sulfur-free and iron-free copper-containing wastewater and application of treatment process in recovery of sulfur-free and iron-free copper-containing wastewater

Abstract

The invention relates to the technical field of wastewater treatment, and discloses a treatment process of sulfur-free and iron-free copper-containing wastewater and application of the treatment process in copper sulfate recovery, the process comprises the following steps: (1) physically filtering the copper-containing wastewater, adjusting the pH value to be less than 4, carrying out oxidation pretreatment, and feeding the copper-containing wastewater into an ion exchange system; and (2) after adsorption, introducing the wastewater into an adsorber containing adsorption particles, applying a magnetic field, carrying out solid-liquid separation, detecting that Cu < 2 + > in the liquid is less than 0.5 mg / L, adjusting the pH value to be neutral, and then discharging. Compared with a traditional copper-containing wastewater treatment process, a polypeptide magnetic adsorption step is added behind an ion exchange system, when Cu < 2 + > in the ion exchange system is about 50 mg / L, Cu < 2 + > is transferred into an adsorber for magnetic adsorption, and the wastewater treatment period can be greatly shortened. In the recovery process of the copper sulfate, the concentration of Cu < 2 + > in the copper-containing wastewater desorption solution is high, and the concentration of impurity ions is low, so that the subsequent recovery and purification process of the copper sulfate is simplified, and the cost is reduced.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment, and particularly relates to the treatment of copper-containing wastewater, specifically to a treatment process for copper-containing wastewater that is free from sulfurization and ironization and its application in copper sulfate recovery. Background Technology

[0002] Wastewater from printed circuit board electroplating, semiconductor and microelectronics manufacturing, dyeing / printing, copper processing, and surface treatment processes contains soluble copper ions (Cu) because these processes only use copper and copper salts and do not introduce sulfide or iron salt reagents. 2+ It is mainly composed of copper complexes (such as copper ammonia complex ions, organic copper complexes), with very little insoluble copper (such as CuO precipitate), and almost no sulfur. 2- Fe 2+ Fe 3+ Other impurities (such as SO4) 2- Cl - It contains NH3, and is therefore called copper-containing wastewater that is free of sulfur and iron.

[0003] Conventional ion exchange or adsorption methods require multiple cycles to achieve effective enrichment of low- to medium-concentration wastewater (adsorption-desorption cycle typically > 8 hours), and the low unit throughput of resins or adsorbents leads to large equipment footprints and extended treatment cycles for large-scale treatment, making it difficult to meet the needs of continuous industrial production. During desorption, existing processes often use a single-concentration acid to desorb saturated resin; however, the strong binding force between copper complexes and resin functional groups makes complete desorption difficult with a single-concentration acid, resulting in residual Cu in the resin. 2+ As the adsorption capacity gradually decreases, the resin needs to be replaced frequently, which not only increases costs but also prolongs the overall treatment cycle due to downtime for resin replacement.

[0004] The copper resources in copper-containing wastewater that is free from sulfur and iron are of high value (it can be recycled into electronic-grade copper sulfate or metallic copper). However, even if the wastewater has few initial impurities, it may still be contaminated by resin leachates, resulting in substandard product purity. This requires multiple purification steps (such as recrystallization and deep impurity removal), further extending the treatment cycle and increasing the process difficulty. Summary of the Invention

[0005] The purpose of this invention is to provide a treatment process for copper-containing wastewater that is free from sulfurization and iron and its application in copper sulfate recovery, so as to solve the problems of low efficiency and long treatment cycle of traditional adsorption methods for copper-containing wastewater, and to provide its application in copper sulfate recovery.

[0006] The present invention achieves the above objectives through the following technical solutions: In a first aspect, the present invention provides a treatment process for copper-containing wastewater that is free of sulfur and iron, comprising the following steps: (1) the copper-containing wastewater is subjected to physical filtration, pH is adjusted to be less than 4, and then is subjected to oxidation pretreatment, and then is subjected to ion exchange; (2) after the Cu 2+ <50 mg / L in the ion exchange system is detected, the wastewater after adsorption is introduced into an adsorber containing adsorption particles, liquid after solid-liquid separation by applying a magnetic field is detected, and the Cu 2+ <0.5 mg / L is detected, and the wastewater is discharged after the pH value is adjusted to be neutral, wherein the adsorption particles are obtained by coating nano Fe3O4 particles with a SiO2 shell, amino modification, and then immobilizing a polypeptide with Cu 2+ adsorption on the surface of the adsorption particles, and the dosage of the adsorption particles is 0.1-5 g / L.

[0007] As a further optimization scheme of the above application, in step (1), the physical filtration comprises coarse filtration, fine filtration and depth filtration in sequence.

[0008] As a further optimization scheme of the above application, in step (1), the oxidation pretreatment is one of Fenton oxidation and ozone oxidation.

[0009] As a further optimization scheme of the above application, in step (1), the adsorption column in the ion exchange system contains at least one of iminodiacetic acid type chelating resin and amino phosphonic acid type chelating resin.

[0010] As a further optimization scheme of the above application, the preparation method of the adsorption particles is as follows: (a) coating a SiO2 shell on the surface of nano Fe3O4 particles and performing amino modification to obtain amino-modified magnetic microspheres, and aldehyde group modification is performed on the surface of the amino-modified magnetic microspheres; (b) mixing and reacting the magnetic microspheres with aldehyde group on the surface with a polypeptide solution to obtain the Cu 2+ functionalized magnetic adsorbent; wherein the amino acid sequence of the polypeptide contains at least two amino acid residues capable of coordinating with Cu 2+ .

[0011] As a further optimization scheme of the above application, in step (a), the nano Fe3O4 particles are uniformly dispersed in an ethanol solution, ammonia water is added, tetraethyl orthosilicate is slowly added dropwise, and Fe3O4@SiO2 is obtained by reacting at room temperature for 1-2 h. APTES is added to the system, and Fe3O4@SiO2-NH2 is obtained by refluxing for 4-6 h. The magnetic separation and washing are performed. The Fe3O4@SiO2-NH2 is dispersed in a borate buffer solution with pH>8, a glutaraldehyde solution is added, and the microspheres are aldehyde group-modified by stirring at room temperature in the dark for 1-2 h. The magnetic separation and washing are performed.

[0012] As a further optimization of the above invention, in step (b), the aldehyde- functionalized microspheres are dispersed in a phosphate buffer with pH > 7, and Cu 2+ The adsorptive polypeptide is added to the solution of the aldehyde-functionalized microspheres, and the mixture is gently shaken at 25-37°C for 4-6h, and then sodium borohydride solution is added, and the mixture is reacted at room temperature for 1-2h to obtain the adsorptive particles.

[0013] As a further optimization of the above invention, the amino acid sequence of the polypeptide comprises at least two histidines (His) or one histidine (His) and one cysteine (Cys).

[0014] As a further optimization of the above invention, the sequence of the polypeptide is any one of the following: (1) Gly-Gly-His-Gly-Gly-Cys; (2) His-Glu-Cys-Phe-Gln-Arg-Phe-Leu-Phe-Gly-Gly-Glu-Ala-Ala; (3) Cys-His-Cys; (4) Asp-Glu-His-Asp-Glu-Cys; (5) His-His-His-His.

[0015] As a further optimization of the above invention, the sequence of the polypeptide is Asp-Glu-His-Asp-Glu-Cys.

[0016] In a second aspect, the present application provides a copper sulfate recovery method based on the above treatment process of the non-sulfurized and non-ironized copper-containing wastewater, comprising the following steps: (I) 3-5% sulfuric acid is used to resolve in the ion exchange system for 1-1.5h, and then is resolved in the adsorber for 10-40min to obtain a first solution, which is fed into a heating kettle; (II) 8-10% sulfuric acid is used to resolve in the ion exchange system for 0.5-1h, and then is resolved in the adsorber for 10-20min to obtain a second solution, which is fed into the heating kettle; (III) >60°C liquid caustic is added into the heating kettle, and the reaction is carried out for 1-3h to form a copper oxide slurry with pH > 13, which is fed into the copper sulfate mother liquor after being washed by plate and frame pressing to a pressing filtrate with TDS < 50mg / L, and 98% sulfuric acid is added into the mother liquor, which is filtered and treated, and then is cooled and crystallized to obtain copper sulfate pentahydrate crystals after centrifugation, and the permeate is a recovered mother liquor for secondary use.

[0017] As a further optimization of the above-mentioned application, the step (II) further comprises sequentially rinsing the resolved ion exchange system and the adsorber, and then circulating a sodium bisulfate solution containing citric acid at a flow rate of 0.5-1 m / s for 10-30 min.

[0018] As a further optimization of the above-mentioned application, the step (III) further comprises cleaning the copper sulfate pentahydrate crystals with a saturated copper sulfate solution, and performing secondary centrifugal separation, and drying the copper sulfate pentahydrate crystals obtained by the secondary separation to obtain the electroplating-grade copper sulfate pentahydrate.

[0019] The application has the following beneficial effects: 1. Compared with the traditional process, the application adds a polypeptide magnetic adsorption step after the ion exchange system, and the Cu 2+ concentration in the ion exchange system is about 50 mg / L, which can greatly reduce the treatment period.

[0020] 2. The copper-containing wastewater flows into the adsorber, and the polypeptide magnetic adsorbent precisely and quickly binds Cu 2+ in water to form a stable complex. Due to its specificity, other common ions are hardly adsorbed, ensuring the treatment accuracy and preventing the generation of copper sludge. After the reaction is completed, an external magnetic field is applied, and all the magnetic adsorbents loaded with copper ions are instantly adsorbed, realizing rapid and efficient solid-liquid separation.

[0021] 3. The ion exchange system and the adsorber are resolved by gradient concentration sulfuric acid (3-5%→8-10%), which not only improves the resolution efficiency and speed, but also ensures high recovery rate of copper ions. After subsequent treatment, electroplating-grade copper sulfate pentahydrate crystals can be directly obtained, simplifying the purification process and reducing the cost. The ion exchange system and the adsorber are protected after resolution, prolonging the service life.

[0022] 4. During the copper sulfate recovery process, the polypeptide magnetic adsorbent only specifically adsorbs copper ions (Cu 2+ ), and has very low adsorption capacity for common ions such as Ca 2+ , Mg 2+ , Na + , etc. in wastewater; which means that the concentration of copper ions in the enriched solution obtained by resolution is very high, while the concentration of impurity ions is very low. The small volume and high concentration copper solution obtained after resolution mainly contains Cu 2+ and SO4 2- , which is almost a pure copper sulfate solution itself, with very low impurity content. After simple concentration and cooling crystallization, reagent-grade or electroplating-grade copper sulfate products can be obtained, greatly simplifying the subsequent recovery and purification process and cost. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1A process flow chart for treating copper-containing wastewater in the prior art; Figure 2 A process flow chart for treating sulfur-free and iron-free copper-containing wastewater in the present application; Figure 3 A process flow chart for copper sulfate recovery in the present application. DETAILED DESCRIPTION

[0024] The present application will be further described in detail below with reference to the accompanying drawings, it is necessary to point out here that the following detailed description is only used to further illustrate the present application, and cannot be understood as limiting the scope of protection of the present application, and those skilled in the art can make some non-essential improvements and adjustments to the present application according to the above application content.

[0025] In at least one embodiment of the present application, a process for treating sulfur-free and iron-free copper-containing wastewater is disclosed, comprising the following steps: (1) After the copper-containing wastewater is subjected to physical filtration, the pH is adjusted to be less than 4, and is subjected to oxidation pretreatment, it is then introduced into an ion exchange system; (2) After detecting that the Cu 2+ <50mg / L in the ion exchange system, the wastewater after adsorption is introduced into an adsorber containing adsorption particles for 10-40min, and the liquid after solid-liquid separation under the action of a magnetic field is detected to have Cu 2+ <0.5mg / L, and is discharged after the pH value is adjusted to be neutral, wherein the adsorption particles are obtained by coating nano Fe3O4 particles with a SiO2 shell, amination, and then immobilizing a Cu 2+ adsorbing polypeptide on the surface, and the amount of the adsorption particles is 0.1-5g / L.

[0026] In step (1), the physical filtration includes coarse filtration (grids / sieve, hydrocyclone), fine filtration (multi-media filter), and depth filtration (filter membrane) in sequence.

[0027] In step (1), the oxidation pretreatment is one of Fenton oxidation and ozone oxidation, and is used for removing organic matter and destroying copper complexes.

[0028] In step (1), the adsorption column in the ion exchange system contains at least one of iminodiacetic acid type chelating resin and amino phosphonic acid type chelating resin, and preferably iminodiacetic acid type chelating resin, and is used for removing free copper and weakly complexed copper; the mode is one of fixed bed multi-column series connection, fluidized bed column, or moving bed multi-column series connection, and is selected according to the actual wastewater treatment capacity; the treatment temperature of the ion exchange system is 30-40℃, and the adsorption time is ≤4h.

[0029] The preparation method of the adsorption particles is as follows: (a) coating a SiO2 shell on the surface of nano Fe3O4 particles and modifying the surface with amino groups to obtain amino-modified magnetic microspheres, and aldehyde-modifying the surface of the amino-modified magnetic microspheres; (b) mixing and reacting the aldehyde-modified magnetic microspheres with a polypeptide solution to obtain Cu 2+ functionalized magnetic adsorbents; wherein the amino acid sequence of the polypeptide comprises at least two amino acid residues capable of coordinating with Cu 2+ .

[0030] In step (a), under nitrogen gas protection, trivalent iron salt FeCl3·6H2O and divalent iron salt FeSO4·7H2O are dissolved in deoxygenated ultrapure water at a molar ratio of 2:1, heated to 60°C, and NaOH solution is quickly added under vigorous stirring, and the reaction is carried out for 0.5 h to obtain black magnetic nano Fe3O4 particles, which are separated by an external magnetic field and washed repeatedly with ultrapure water and ethanol until neutral.

[0031] In step (a), the nano Fe3O4 particles are uniformly dispersed in an ethanol solution, ammonia water is added, and tetraethyl orthosilicate is slowly added dropwise, and the reaction is carried out at room temperature for 1-2 h to obtain Fe3O4@SiO2, (3-aminopropyl) triethoxysilane APTES is added to the system, and the reaction is carried out under reflux for 4-6 h to obtain Fe3O4@SiO2-NH2, which is magnetically separated and washed; Fe3O4@SiO2-NH2 is dispersed in a borate buffer solution with pH>8, and glutaraldehyde solution is added, and the reaction is carried out at room temperature under light shielding and stirring for 1-2 h to aldehyde-modify the surface of the microspheres, which are magnetically separated and washed.

[0032] In step (b), the aldehyde-modified microspheres are dispersed in a phosphate buffer solution with pH>7, and Cu 2+ polypeptides with adsorption are added, and the reaction is carried out under gentle shaking at 25-37°C for 4-6 h, and then sodium borohydride solution is added, and the reaction is carried out at room temperature for 1-2 h to obtain adsorbed particles.

[0033] The N-terminal and C-terminal of the polypeptide sequence comprise at least two histidines His or one histidine His and one cysteine Cys, such as: H2N-Gly-Gly-His-Gly-Gly-Cys-COOH, H2N-His-Glu-Cys-Phe-Gln-Arg-Phe-Leu-Phe-Gly-Gly-Glu-Ala-Ala-COOH, H2N-Cys-His-Cys-COOH, H2N-Asp-Glu-His-Asp-Glu-Cys-COOH, H2N-His-His-His-His-COOH.

[0034] In at least one embodiment of the present application, a copper sulfate recovery method is disclosed, based on the above-mentioned treatment process of non-sulfurized and non-ironized copper-containing wastewater, comprising the following steps: (I) When the ion exchange system is saturated (Cu 2+ > 50 mg / L), 3-5% sulfuric acid is used to enter the ion exchange system for 1-1.5 hours, and then enters the adsorber for 10-40 minutes to obtain a first solution, which is then put into a heating kettle; (II) Then 8-10% sulfuric acid is used to enter the ion exchange system for 0.5-1 hour, and then enters the adsorber for 10-20 minutes to obtain a second solution, which is then put into the heating kettle; (III) Liquid alkali at > 60°C is added to the heating kettle, and the reaction is carried out for 1-3 hours to form a copper oxide slurry with pH > 13. After being washed by plate and frame pressing to a pressing filtrate TDS < 50 mg / L, it is put into a copper sulfate mother liquor, and 98% sulfuric acid is added to the mother liquor. After filtration treatment, cooling crystallization is carried out, and copper sulfate pentahydrate crystals are obtained after centrifugation. The permeate is a recovered mother liquor for secondary use.

[0035] Step (I) further comprises detecting Fe 2+ and Fe 3+ in the desorption liquid of the adsorber, and when the concentration exceeds 10 mg / L, the adsorption particles in the adsorber are replaced, and the desorption liquid is treated to remove iron (① sedimentation tank: sodium hydroxide is added to adjust the pH to about 9, so that iron forms Fe(OH)3 precipitate, while copper remains in ionic state; ② adsorption tank: strong basic anion exchange resin).

[0036] Step (II) further comprises sequentially flushing the ion exchange system and the adsorber after desorption, and then circulating 0.05 mol / L citric acid and 0.1-0.5 mol / L sodium bisulfate solution at a flow rate of 0.5-1 m / s for 10-30 minutes.

[0037] Step (III) further comprises washing the copper sulfate pentahydrate crystals with saturated copper sulfate solution, and performing secondary centrifugal separation. The copper sulfate pentahydrate crystals obtained by secondary separation are dried to obtain electroplating grade copper sulfate pentahydrate.

[0038] 1. Description The copper-containing wastewater in the present application is derived from wastewater generated during copper processing and surface treatment, with Cu concentration ranging from 10-1000 mg / L (rounded), S 2- , Fe 2+ , and Fe 3+ all < 5 mg / L.

[0039] The sewage treatment process simulation experiment system comprises a filter tank (2m x 2m x 0.8m), a regulating reaction tank (1m x 2m x 0.8m), an ion exchange tank (3m x 1m x 0.8m, single group of mobile adsorption column), an adsorption tank (adsorber is a cylinder with a size of 0.8 2 m x 0.8m, and a discharge temporary storage tank (2m x 2m x 0.8m).

[0040] The method used in the present application is a conventional method known to those skilled in the art, and the reagents and other materials used are commercially available products, unless otherwise specified. The instruments used are conventional instruments known to those skilled in the art, unless otherwise specified.

[0041] 2. Method 2.1 Treatment of copper-containing wastewater Example 1 The copper concentration in the copper-containing wastewater in this example is 682±5mg / L, and the treatment process comprises the following steps: (1) The copper-containing wastewater from the production line is sequentially subjected to coarse filtration, fine filtration and depth filtration, and then enters the regulating reaction tank, and the pH is adjusted to 3 using 20% sulfuric acid (the pH is monitored in real time by an online pH meter, and the pH fluctuation is controlled to be ±0.5), and then ozone is added for oxidation pretreatment (the ozone dosage is 1.5 times the COD value of the copper-containing wastewater), and then the wastewater enters the ion exchange system containing imino diacetic acid type chelating resin adsorption column for adsorption, and the temperature of the ion exchange system is 30℃; (2) After 2h of adsorption, it is detected that the Cu 2+ <50mg / L in the ion exchange system, the wastewater is introduced into the adsorber containing adsorption particles (3.5g / L), mechanical stirring is performed for 25min, then a magnetic field (electromagnet) is applied to fix the adsorption particles, solid-liquid separation is realized, and the separated liquid is detected to have Cu 2+ <0.5mg / L, Fe 3+ <0.5mg / L, and after adjusting the pH value to 7.1±0.5 using 20% sodium hydroxide, it is discharged. 2+ The adsorption particles are obtained after immobilizing the polypeptide (H2N-Cys-His-Cys-COOH) on the surface of Fe3O4@SiO2-NH2.

[0042] Comparative Example 1 The copper concentration in the copper-containing wastewater in this example is 617±5mg / L, and the treatment process is as follows: The copper-containing wastewater coming from the production line was sequentially subjected to rough filtration, fine filtration and deep filtration, and then entered the adjusting reaction tank, and the pH was adjusted to 3 by 20% sulfuric acid (real-time monitoring by online pH meter, and the pH fluctuation was controlled to be ±0.5), and then ozone was added for oxidation pretreatment (the ozone dosage was 1.5 times of the COD value of the copper-containing wastewater), and then the wastewater entered the ion exchange system containing imino diacetic acid type chelating resin adsorption column for adsorption, and the temperature of the ion exchange system was 30°C, and after 3.5 h, the Cu 2+ concentration was 1.68 mg / L, and after 4.2 h, the Cu 2+ concentration was 0.85 mg / L, and the subsequent range fluctuation was not more than 0.01 mg / L.

[0043] Comparative Example 2 The Cu concentration in the copper-containing wastewater in the present comparative example was 645±5 mg / L, and the treatment process was as follows: (1) The copper-containing wastewater coming from the production line was sequentially subjected to rough filtration, fine filtration and deep filtration, and then entered the adjusting reaction tank, and the pH was adjusted to 3 by 20% sulfuric acid (real-time monitoring by online pH meter, and the pH fluctuation was controlled to be ±0.5), and then ozone was added for oxidation pretreatment (the ozone dosage was 1.5 times of the COD value of the copper-containing wastewater), and then the wastewater entered the ion exchange system containing imino diacetic acid type chelating resin adsorption column for adsorption, and the temperature of the ion exchange system was 30°C; (2) After 2 h of adsorption, it was detected that the Cu 2+ concentration in the ion exchange system was less than 50 mg / L, and the wastewater was passed into the adsorber containing activated carbon adsorption filler (3.5 g / L), and after stirring for 40 min, solid-liquid separation was performed for 20 min, and the separated liquid was detected to have a Cu 2+ concentration of 0.73 mg / L.

[0044] From the treatment time and the Cu 2+ concentration in the effluent, it can be seen that the single ion exchange system is difficult to balance the copper removal efficiency and depth in the treatment of copper-containing wastewater, and the single chelating resin is also difficult to balance the efficiency and depth. The application of polypeptide magnetic adsorbent to the treatment process of copper-containing wastewater can precisely capture low-concentration Cu 2+ through coordination bond by specific surface-immobilized polypeptide (containing His, Cys and other amino acids), and still has strong adsorption capacity for residual copper of 0.5-1 mg / L, and the concentration can be reduced to 0.07 mg / L from the effluent of the chelating resin in only 25 minutes, and the depth copper removal efficiency is increased by more than 10 times. The total treatment time of Example 1 is shortened by 47% compared with Comparative Example 1 and by 29% compared with Comparative Example 2, which means that the treatment amount per unit time is increased, the equipment investment and operation cost are reduced, and the effluent concentration is far lower than the discharge standard.

[0045] 2.2 Effect of polypeptide-containing adsorption particles on the treatment of copper-containing wastewater The adsorption particles are prepared according to the following steps: (a) Under the protection of nitrogen gas, trivalent iron salt FeCl3·6H2O and divalent iron salt FeSO4·7H2O are dissolved in deoxygenated ultrapure water at a molar ratio of 2:1, heated to 60°C, and NaOH solution is quickly added under vigorous stirring, and the reaction is carried out for 0.5h to obtain black magnetic nano Fe3O4 particles, which are separated by an external magnetic field and washed repeatedly with ultrapure water and ethanol until neutral; (b) The nano Fe3O4 particles are uniformly dispersed in an appropriate amount of ethanol solution (v / v ethanol: water = 5:1), ultrasonically dispersed, and sufficient ammonia water (25% mass fraction) is added, and tetraethyl orthosilicate TEOS (1.5mLTEOS / 1gFe3O4) is slowly added dropwise, and the reaction is carried out at room temperature for 2h to obtain Fe3O4@SiO2, (3-aminopropyl) triethoxysilane APTES (v / v APTES / TEOS = 1:1) is added to the system, and the reaction is carried out under reflux for 6h to obtain Fe3O4@SiO2-NH2, which is magnetically separated and washed; Fe3O4@SiO2-NH2 is dispersed in a borate buffer solution with pH = 8, 25% glutaraldehyde solution (final concentration v / v is 1.0%-1.5%) is added, and the reaction is carried out at room temperature in the dark for 1-2h to aldehyde the surface of the microspheres, which are magnetically separated and washed; (c) The freeze-dried polypeptide powder is weighed or synthesized in advance, dissolved in PBS buffer with pH = 7.4 to prepare a 1mM polypeptide solution, the aldehyde-modified microspheres are dispersed in a phosphate buffer solution with pH = 7.4, and an excess of polypeptide solution is added, and the reaction is carried out at 37°C under gentle shaking for 4h, and then an equal amount of sodium borohydride solution is added, and the reaction is carried out at room temperature for 2h to obtain the adsorption particles.

[0046] The sequence of the polypeptide is shown in Table 1: Table 1. Polypeptide sequence

[0047] According to the adsorption particles obtained above, the same batch of equal volume of copper-containing wastewater (Cu concentration is 682±5mg / L) in the production line is treated according to the process of Example 1 of 2.1, which is respectively Example 2-5, and when the Cu 2+ concentration in the wastewater is detected to be less than 50mg / L, it enters the adsorber (at least 10 detection points are set), and the time and corresponding concentration when the Cu 2+ concentration is stable and less than 0.5mg / L are obtained, and the conductivity of the wastewater is detected, as shown in Table 2: Table 2. Stable concentration of Cu 2+ and time used

[0048] The above data clearly shows that the amino acid composition and sequence structure of the polypeptide are the core factors determining the performance of the magnetic adsorbent, rather than the length of the peptide chain alone. Among them, the short peptide sequence containing "acidic amino acid (Asp / Glu) + His + Cys" performs best, which can not only remove copper ions deeply through multiple actions, but also quickly reach adsorption equilibrium. This shows that by reasonably matching functional groups (electrostatic assistance + multiple coordination), efficient and deep copper ion removal can be achieved while ensuring low cost.

[0049] 2.3 Copper sulfate recovery On the basis of the processes of Examples 1-5, when the ion exchange system is saturated (the effluent Cu 2+ > 50 mg / L), the copper sulfate recovery is carried out according to the following steps: (1) 5% sulfuric acid is used to elute the ion exchange system, and then the elution solution is introduced into the adsorber to obtain a first solution, which is introduced into the heating kettle; (2) 10% sulfuric acid is used to elute the ion exchange system, and then the elution solution is introduced into the adsorber to obtain a second solution, which is introduced into the heating kettle; (3) > 60°C and 3.5 mol / L liquid alkali is added to the heating kettle, and the reaction is carried out for 2 h to form a copper oxide slurry with pH = 13.4. After washing by plate and frame pressing to a pressing filtrate TDS < 50 mg / L, it is put into the copper sulfate mother liquor, and 98% sulfuric acid is added to the mother liquor (so that the hydrogen ion concentration of the mother liquor added with copper oxide is controlled at 4.3-4.5 mol / L). After filtration treatment, cooling crystallization is carried out, and after centrifugation, copper sulfate pentahydrate crystals are obtained, and the permeate is the recovered mother liquor for secondary use.

[0050] On the basis of the processes of Comparative Examples 1-2, the ion exchange system and the adsorber are eluted according to the following steps: Comparative Example 1: 5% sulfuric acid is used to elute the ion exchange system, and the elution solution is introduced into the heating kettle; then 10% sulfuric acid is used to elute the ion exchange system.

[0051] Comparative Example 2: 5% sulfuric acid is used to elute the ion exchange system, and then the elution solution is introduced into the activated carbon adsorption filler adsorber; then 10% sulfuric acid is used to elute the ion exchange system, and then the elution solution is introduced into the activated carbon adsorption filler adsorber.

[0052] Meanwhile, a control group is provided: based on the process parameters of Example 1, 8% sulfuric acid is used to elute the ion exchange system, and then the elution solution is introduced into the adsorber.

[0053] The Cu 2+ concentration in the liquid system in Examples 1-5 and Comparative Examples 1-3 is stable, and the elution time and elution rate (total elution liquid Cu 2+ concentration / (total Cu2+ Concentration - Cu in effluent wastewater 2+ Concentration), the results are shown in Table 3: Table 3. Cu in liquid system 2+ Concentration stable analysis time

[0054] As can be seen from the above table, using low concentration sulfuric acid first and then high concentration sulfuric acid for desorption can significantly reduce the desorption time and increase the desorption rate. Further, it is found that the longer the sequence of polypeptide, the longer the desorption time in the adsorber, and the polypeptide containing His has a generally higher desorption efficiency, especially the pure His sequence, the coordination bond between the imidazole ring of His and Cu 2+ is easily broken by H + under acidic conditions; while the polypeptide containing Cys has a slightly longer desorption time, because the coordination bond between the thiol group (-SH) of Cys and Cu 2+ is stronger and needs longer time to be replaced by H + in sulfuric acid.

[0055] In combination with 2.1-2.3, it is concluded that in the treatment of copper-containing wastewater, if both adsorption efficiency and desorption speed are considered, the polypeptide magnetic adsorbent containing "H2N-Asp-Glu-His-Asp-Glu-Cys-COOH" is preferred.

[0056] 2.4 Set up several simulation pools 1m x 1m x 0.8m, the specific settings are shown in Table 4: Table 4. Simulation pool settings

[0057] Use 20% sulfuric acid to adjust the pH of the simulated copper-containing wastewater to 3, then enter simulation pool A, and detect that Cu 2+ <50mg / L in simulation pool A, then enter simulation pool B, Cu 2+ <0.5mg / L is discharged, and Cu 2+ removal rate is obtained. After detecting that simulation pool A is saturated, use 10% sulfuric acid to enter simulation pool A for desorption, and then enter simulation pool B for desorption. After desorption, use a solution containing 0.05mol / L citric acid and 0.35mol / L sodium bisulfate to circulate simulation pool A and simulation pool B at a flow rate of 0.5-1m / s for 20min, repeat the simulation of copper-containing wastewater treatment and desorption process, complete 100 batches of simulated wastewater treatment within 30 days, and use the change of Cu 2+ removal rate as the evaluation index of recycling.

[0058] Table 5. Change of Cu 2+ removal rate

[0059] By comparing group ①, ②, ⑥ and ③-⑤, ⑦, it can be seen that the passivation treatment of iminodiacetic acid type chelating resin adsorption column and adsorption particles with 0.05 mol / L citric acid and 0.35 mol / L sodium bisulfate solution can reduce the hydrolysis of functional groups, slow down the decay rate of adsorption capacity, and prolong the service life. By comparing groups ③-⑤, it can be seen that the polypeptides of group ③ (Gly-Gly-His-Gly-Gly-Cys) and group ④ contain flexible spacers (Gly) or acidic amino acids (Asp / Glu). When regenerated with citric acid-sodium bisulfate, small molecules of regenerant are more easily penetrated and replaced by residual Cu 2+ , reducing the blockage of adsorption sites, so the removal rate is higher (97.5%-97.6%) after 100 batches. Although group ③ has a fast elution rate, it lacks auxiliary groups, and some imidazole rings may be oxidized or irreversibly combined to cause activity decline after long-term circulation, so the stability is slightly inferior to that of groups ③ and ④. By comparing group ⑦ and ③-⑤, it can be seen that the mechanical strength of the polypeptide magnetic adsorbent is high, and it is not easy to break during circulation. The magnetic field assisted separation reduces the loss, and the swelling in water is not easy to occur. Compared with activated carbon, the effect is more practical.

[0060] Further, the copper sulfate pentahydrate crystals are washed with saturated copper sulfate solution and subjected to secondary centrifugal separation. The copper sulfate pentahydrate crystals obtained by the secondary separation are dried, and electroplating grade copper sulfate pentahydrate can also be obtained.

[0061] The above-described embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the scope of the patent of the present application. It should be noted that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of protection of the present application.

Claims

1. A treatment process for copper-containing wastewater that is free of sulfur and iron, characterized in that, Includes the following steps: After physical filtration and pH adjustment to <4, copper-containing wastewater undergoes oxidation pretreatment before entering the ion exchange system. Cu was detected in the ion exchange system 2+ After the concentration of Cu in the wastewater exceeds 50 mg / L, the wastewater is passed into an adsorber containing adsorbent particles. A magnetic field is applied to separate the solid and liquid phases, and the resulting liquid is then tested for Cu. 2+ <0.5 mg / L, adjust pH to neutral before discharge, wherein the adsorbed particles are nano-Fe3O4 particles coated with a SiO2 shell, aminated, and then immobilized on the surface to adsorb Cu. 2+ It is obtained by adsorbing polypeptides.

2. The treatment process for copper-containing wastewater without sulfur or iron as described in claim 1, characterized in that, In step (1), the physical filtration includes coarse filtration, fine filtration and deep filtration in sequence.

3. The treatment process for sulfur-free and iron-free copper-containing wastewater according to claim 1, characterized in that, In step (1), the oxidation pretreatment is either Fenton oxidation or ozone oxidation.

4. The treatment process for sulfur-free and iron-free copper-containing wastewater according to claim 1, characterized in that, In step (1), the adsorption column in the ion exchange system contains at least one of iminodiacetic acid chelating resin and aminophosphonic acid chelating resin.

5. The treatment process for sulfur-free and iron-free copper-containing wastewater according to claim 1, characterized in that, The method for preparing the adsorbent particles is as follows: (a) A SiO2 shell is coated on the surface of nano Fe3O4 particles and aminated to obtain aminated magnetic microspheres, and the surface of the aminated magnetic microspheres is aldehyde-modified. (b) The surface-aldehyde-modified magnetic microspheres are mixed with a polypeptide solution and reacted to obtain the Cu. 2+ Functionalized magnetic adsorbent; wherein the amino acid sequence of the polypeptide contains at least two amino acids that can interact with Cu. 2+ Coordinated amino acid residues.

6. The treatment process for sulfur-free and iron-free copper-containing wastewater according to claim 5, characterized in that, In step (a), nano-Fe3O4 particles are uniformly dispersed in an ethanol solution, ammonia is added, and tetraethyl orthosilicate is slowly added dropwise. The reaction is carried out at room temperature for 1-2 hours to obtain Fe3O4@SiO2. APTES is added to the system, and the reaction is refluxed for 4-6 hours to obtain Fe3O4@SiO2-NH2. The mixture is then magnetically separated and washed. The Fe3O4@SiO2-NH2 is dispersed in a borate buffer solution with pH > 8, and glutaraldehyde solution is added. The mixture is stirred at room temperature in the dark for 1-2 hours to aldehyde-modify the surface of the microspheres. The mixture is then magnetically separated and washed.

7. The treatment process for sulfur-free and iron-free copper-containing wastewater according to claim 6, characterized in that, In step (b), the aldehyde-modified microspheres are dispersed in a phosphate buffer solution with pH > 7, and Cu is added. 2+ The adsorbent polypeptide is reacted with gentle shaking at 25-37°C for 4-6 hours, and then sodium borohydride solution is added and reacted at room temperature for 1-2 hours to obtain the adsorbent particles.

8. The treatment process for sulfur-free and iron-free copper-containing wastewater according to claim 7, characterized in that, The amino acid sequence of the polypeptide contains at least two histidine residues (His) or one histidine residue (His) and one cysteine ​​residue (Cys).

9. The treatment process for sulfur-free and iron-free copper-containing wastewater according to claim 8, characterized in that, The sequence of the polypeptide is any one of the following: (1) Gly-Gly-His-Gly-Gly-Cys; (2) His-Glu-Cys-Phe-Gln-Arg-Phe-Leu-Phe-Gly-Gly-Glu-Ala-Ala; (3) Cys-His-Cys; (4)Asp-Glu-His-Asp-Glu-Cys; (5) His-His-His-His.

10. The treatment process for sulfur-free and iron-free copper-containing wastewater according to claim 9, characterized in that, The sequence of the polypeptide is Asp-Glu-His-Asp-Glu-Cys.

11. A method for recovering copper sulfate, based on the treatment process for copper-containing wastewater without sulfur or iron as described in any one of claims 1-10, characterized in that, Includes the following steps: (I) Use 3-5% sulfuric acid to enter the ion exchange system for 1-1.5h to decompose, and then enter the adsorber for 10-40min to obtain the first solution, which is then transferred to the heating kettle; (II) Then, 8-10% sulfuric acid is introduced into the ion exchange system for 0.5-1h to decompose, and then it is introduced into the adsorber for 10-20min to obtain the second solution, which is then transferred to the heating kettle; (III) Add liquid alkali at >60℃ to the heating kettle and react for 1-3 hours to form copper oxide turbidity with pH >13. After plate and frame pressing and washing until the TDS of the pressing filtrate is <50mg / L, add it to the copper sulfate mother liquor and add 98% sulfuric acid to the mother liquor. After filtration, cool and crystallize. After centrifugation, copper sulfate pentahydrate crystals are obtained. The permeate is the mother liquor for secondary use.

12. The treatment process for sulfur-free and iron-free copper-containing wastewater according to claim 11, characterized in that, Step (II) also includes rinsing the ion exchange system and adsorber after analysis in sequence, and then circulating the solution of sodium bisulfate containing citric acid at a flow rate of 0.5-1 m / s for 10-30 min.

13. The treatment process for sulfur-free and iron-free copper-containing wastewater according to claim 11, characterized in that, Step (III) further includes washing the copper sulfate pentahydrate crystals with a saturated copper sulfate solution and performing a second centrifugal separation. The copper sulfate pentahydrate crystals obtained from the second separation are then dried to obtain electroplating grade copper sulfate pentahydrate.

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